Objective： To study the effect of the non-depolarizing muscle relaxants rocuronium and cis-atracurium on uterine smooth muscle contraction of isolated rat at the labor stages. Methods：SD rats at labor stages were killed by cervical off. The uterine smooth muscle tissue was placed into the in vitro devices. The depolarized muscle relaxants were given to the bath and converted by the transducer. The value of the smooth muscle contraction were recorded in the multichannel physiological signal analysis system. The value of smooth muscle contraction were recorded before the oxytocin antagonist and muscle relaxant, neostigmine were used in smooth muscle. For comparison of the drugs, the SPSS17 was used in data processing of smooth muscle contraction（ P＜0.05）. Results： Rocuronium and cis-atracurium had significantly inhibited effect on the uterine smooth muscle of isolated rat at labor stages. There was no significant difference in statistics between the two groups（ P＜0.05）. This contractil inhibition could be eased by oxytocin and neostigmine（ P ＜0.05）. Conclusion： Rocuronium or cis-atracurium prossessed antagonism for M receptor, so they could produce inhibitory effect on the uterine smooth muscle of isolated rat at laboe stages. Oxytocin and neostigmine could relax uterine smooth muscle inhibition caused by non-depolarizing muscle relaxants. Acute severe obstetrics patients in general anesthesia with muscle relaxants should be taken to avoid residual effects may be due to uterine inertia.